The rules of this challenge come from a recent Reddit post and are restated here.
Given a numbered grid, the challenge is to draw a path through the points in the grid subject to the following constraints:
- The path takes a straight line between points.
- The path does not cross itself (except at points) nor retrace any segment.
- The path must visit every point in numbered order, but it is allowed to visit intermediate points. More precisely, the sequence of numbers the path visits must contain $1,2,\dots,9$ as a subsequence (see example).
As an example (taken from the Reddit post), the following is a valid solution path for this particular numbered grid.
The order the path visits the vertices is 1, 7, 2, 3, 4, 2, 9, 5, 3, 6, 7, 4, 6, 8, 3, 9, and the bold subsequence shows that every point is visited in numbered order. Try tracing the path on paper to see for yourself.
Find a path as described for the following numbered grid.
[This puzzle does not rely on tricks so, for example, the points are intended to be in a perfectly aligned grid.]